Incandescent filament electric lamp



Filed Aug. 31, 1929 INVENTOR 19.5. qusrl/v ATTORN I Patented Oct. 9, 1934 1,975,844 INCANDESOENT mamm'r nmc'rmc LAMP Daniel SQ Gustin, Bloomfield, N. J.,

assignor to Westinghouse Lamp Company, a corporation of Pennsylvania Application August 31, 1929, Serial No. 389,682 3 Claims. (01. 176-16) The present invention relates to incandescent connection with talking moving picture apparatus.

According to my invention I provide a lamp with a ribbon shield of refractory metal which surrounds the filament. The shield is heated to incandescence by radiation from the filament and serves as a source of light for a photo-electric cell. The ribbon shield affords fiat surfaces which are ideal for projection purposes.

It is an objectof my invention to provide a lamp construction adapted to operate on alternating current in talking moving picture apparatus without the resulting hum from the current heating cycle.

It is another object of my invention to provide a lamp having a plane surfaced indirectly heated refractory member.

Further objects of the invention are the provision of a ribbon or sheet-like refractory member which shall be indirectly heated to eliminate hot spots usually present in a current carrying ribbon filament due to its non-uniformity in cross-section and the simplification of the lamp parts.

While the advantages of my novel lamp make it adaptable to various applications, its greatest usefulness is found in connection with projection apparatus, and in the present case we have set forth the'application to talking moving picture projection apparatus.

It is the usual practice in the projection of talking moving pictures to pass an intense light from as constant assource as it is possible to obtain through a moving film to a photo-electric cell, which causes a current proportional to the intensity of the light passed through the film to flow to the sound reproduction means.

A constant direct current source is well adapted for this purpose but in general it is not as readily obtainable as an alternating current supply. This usually necessitates a process of rectification from alternating to direct current. This process involves a heavy initial cost and because of the low 'efliciency of rectifiers in general, a heavy maintenance cost.

Since an alternating current source of supply is so readily obtainable many attempts have been made to employ this source of light. Alternating current filaments are not constant and causes a slight flickering of the lamp. This flickering or variation of intensity of the light is carried through the film to the photo-electric cell and causes a corresponding variation in the current to the sound reproduction means. This results in humming.

It has been-proposed to increase the size of the filament so that the heat lag will be lessened. This, however, is only partially satisfactory.

For a better understanding of my invention reference may be had to the following description taken in connection with the accompanying drawing, in which Fig. 1 is an elevational view of the lamp having a portion of the envelope broken away to show the arrangement of the'filament and refractory member.

Fig. 2 is a similar view on an enlarged scale of parts shown in Fig. 1, and

Fig. 3 is an enlarged sectional view taken on line III-III in Fig. 1.

Referring tothe drawing 1 indicates a nitrogen filled envelope of a lamp constructed in accordance with my invention having a suitable base 2 which is connected by suitable lead wires 3 and 4 to a pair of standards 5 on which a filament 6 is mounted. v

The filament 6 is preferably made of large cross section wire of high electrical resistance so that when heated to incandescence the comparatively large weight of metal will cause it to heat and cool slowly. A tubular member '7 of sheet refractory metal surrounds the filament 6. The member 7 is closely spaced from the filament 6 which latter in the present invention is shown as a double coil of wire. A suitable spud 8 supports the member '7 from a stem 9 fixing the relative positions of the filament and member 7. Thin sheet refractory metals such as tungsten, molybdenum, nickel and the like,-are preferably employed in constructing the member 7.

I have shown the member 7 as rectangular in cross section since this construction affords two plane surfaces which are to be used as light sources. The filament supports 5 are disposed along the sides of the rectangular member '7 so that they will afford no obstructions to the light projected from the the two surfaces above mentioned.

In operation the filament 6 is heated by an alternating current and the member '7 is heated to incandescence by radiation from the filament 6.

The indirect heating of member '7 increases the time lag, that is to say the rate of heating and cooling of the same. This causes the temperature of the member 'I-to remain practically constant. thus giving a constant source of light. The indirect heating of member '7 also avoids hot spots in the same which would be caused if the alternating current were passed directly through the same.

In accordance with the provisions of the patent statutes, I have described the purpose of my invention together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means. a

What is claimed is:

1. An electric lamp comprising an enclosing glass envelope, two electrical conductors extending interiorly and exteriorly of. said envelope, means within said envelope and spaced from the interior wall thereof, said means connected to said conductors and adapted to be incandesced by the passage of electric current through said conductors and said means, a refractory metal body also within said envelope and located in the space between said first mentioned means and the interior wall of said envelope, said refractory metal body adapted to become incandesced by energy radiated from said first men-- tioned means, the major portion of the space between said first mentioned means and said refractory metal body being substantially unobstructed and the major portion of the space between said refractory metal body and the interior wall of said envelope also being substantially unobstructed.

' 2. An electric lamp comprising an enclosing glass envelope, two electrical conductors extending interiorly and exteriorly ofsaid envelope, means within said envelope and spaced from the interior wall thereof, said means connectedrtos said conductors and adapted to be incandesced metal body, the shortest by the passage of electric current through said conductors and said means, a refractory metal body also within said envelope and located in the,

space between said first mentioned means and the interior wall of said envelope, said refractory metal body adapted to become incandesced, by energy from said vfirst mentioned means, the shortest distance between said first mentioned means and said refractory metal body being relatively small as compared to the shortest distance between the refractory metal body and theenvelope, the major portion of the space between said first mentioned means and said refractory metal body being substantially unobstructed and the major portion of the space between said refractory metal body and the interior wall of said envelope also being substantially unobstructed.

3. An electric lamp comprising an enclosing envelope having a press, two conductors extending interiorly and exteriorly of said press, a coiled filament within the envelope and supported by said conductors, a hollow refractory metal body surrounding said filament, said body being rectangular in cross section and supporting means extending from said press and secured to said distance between said filament and said body being relatively small as compared to the distance between said body and the interior wall of said envelope, the major portion of the space between said filament and said body being substantially unobstructed and the major portion of the space between said body and said envelope structed.

DANIEL s.- GUS'I'INQ also being substantially unob- 

